Field of Invention
The present application relates to wheel or tire chocks that are lockable in an engaged position to prevent theft, and chocks that have improved methods to quickly adjust the engagement position.
Prior Art
Wheel or tire chocks are used to prevent a trailer or vehicle from moving back and forth when at rest. Tire chocks are placed between the wheels and expanded to apply pressure to both wheels in opposite directions, therefore preventing them from moving or rocking.
One problem with current tire chocks is that is takes time to make the adjustment to apply pressure to the tires. Another problem is that they are easily stolen, as the tire chock can be removed by someone with the correct size wrench.
There is a need for an improved tire chock that addresses the problems of adjustability and theft.
U.S. Pat. No. 8,365,875 to Garceau describes a tire chock having an at least partially threaded rod; a first trunnion having an aperture therethrough that receives the rod; first and second locking members, one locking member being rotatably fixed relative to the rod, the other locking member being rotatably fixed relative to the first trunnion. A tire chock may alternatively have an at least partially threaded rod; an upper trunnion rotatably attached to the rod; a lower trunnion threadedly attached to the rod, the lower trunnion translating axially relative to the rod upon rotation of the rod relative to the lower trunnion; a pair of linkage arms, the pair of linkage arms forming an X-shape, each linkage arm being connected to the lower trunnion by a drive arm and being connected to the upper trunnion by a support arm, wherein, as the rod is rotated relative to the lower trunnion, the linkage arms expand or contract.
FIGS. 1A and 1B show two embodiments described in the '875 patent. The device is expanded into position by turning nut 32 or 132. The device may be locked by aligning apertures:                “As illustrated in FIGS. 9-10, lower locking member 128 and upper locking member 130 may comprise a plurality of apertures 136, 138 therethrough. Since lower locking member 128 may be fixed relative to upper trunnion 124 and handle 134; and upper washer 130 may be fixed relative to threaded rod 120 and nut 132, tire chock 110 is able to be locked in any position by aligning aperture 136 in lower locking member 128 with aperture 138 in upper locking member 130 and inserting a lock or pin through both apertures 136, 138.”        
Adjusting the width of the '875 device is relatively slow because the threaded rod must be rotated with respect to a lower trunnion:                “Lower trunnion 22 may be threadedly connected to threaded rod 20 such that as the threaded rod 20 is rotated relative to lower trunnion 22, the trunnion 22 translates axially relative to the threaded rod 20. Tire chock 10 may additionally comprise upper trunnion 24 that is rotatably connected to the threaded bar 20.”        
As described below, one aspect of the current invention is to permit a scissor frame to be quickly set to an approximate desired position without requiring the threaded rod to be turned. In the embodiments described below, a freely rotatable nut is used to set an expansion limit of the device which is just narrower than the final locked width of the device. A top head or nut is then turned, or a cam is engaged, to provide the final adjustment to lock the chock in place.